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/*
* Copyright 2000-2016 Vaadin Ltd.
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.vaadin.ui.renderers;
import java.util.Objects;
import com.vaadin.server.AbstractClientConnector;
import com.vaadin.server.AbstractExtension;
import com.vaadin.server.JsonCodec;
import com.vaadin.ui.Grid;
import com.vaadin.ui.Grid.Column;
import com.vaadin.ui.renderers.ClickableRenderer.RendererClickEvent;
import elemental.json.JsonValue;
/**
* An abstract base class for server-side
* {@link com.vaadin.ui.renderers.Renderer Grid renderers}.
*
* <p>
* This class currently extends the AbstractExtension superclass, but this fact
* should be regarded as an implementation detail and subject to change in a
* future major or minor Vaadin version.
*
* @param <T>
* the grid type this renderer can be attached to
* @param <V>
* the type this renderer knows how to present
*/
public abstract class AbstractRenderer<T, V> extends AbstractExtension
implements Renderer<V> {
private final Class<V> presentationType;
private final String nullRepresentation;
/**
* Creates a new renderer with the given presentation type and null
* representation.
*
* @param presentationType
* the data type that this renderer displays, not
* <code>null</code>
* @param nullRepresentation
* a string that will be sent to the client instead of a regular
* value in case the actual cell value is <code>null</code>. May
* be <code>null</code>.
*/
protected AbstractRenderer(Class<V> presentationType,
String nullRepresentation) {
Objects.requireNonNull(presentationType,
"Presentation type cannot be null");
this.presentationType = presentationType;
this.nullRepresentation = nullRepresentation;
}
/**
* Creates a new renderer with the given presentation type. No null
* representation will be used.
*
* @param presentationType
* the data type that this renderer displays, not
* <code>null</code>
*/
protected AbstractRenderer(Class<V> presentationType) {
this(presentationType, null);
}
/**
* This method is inherited from AbstractExtension but should never be
* called directly with an AbstractRenderer.
*/
@Deprecated
@Override
@SuppressWarnings("rawtypes")
protected Class<Column> getSupportedParentType() {
return Column.class;
}
/**
* This method is inherited from AbstractExtension but should never be
* called directly with an AbstractRenderer.
*/
@Deprecated
@Override
protected void extend(AbstractClientConnector target) {
super.extend(target);
}
@Override
public Class<V> getPresentationType() {
return presentationType;
}
@Override
public JsonValue encode(V value) {
if (value == null) {
return encode(getNullRepresentation(), String.class);
} else {
return encode(value, getPresentationType());
}
}
/**
* Null representation for the renderer
*
* @return a textual representation of {@code null}
*/
protected String getNullRepresentation() {
return nullRepresentation;
}
/**
* Encodes the given value to JSON.
* <p>
* This is a helper method that can be invoked by an {@link #encode(Object)
* encode(T)} override if serializing a value of type other than
* {@link #getPresentationType() the presentation type} is desired. For
* instance, a {@code Renderer<Date>} could first turn a date value into a
* formatted string and return {@code encode(dateString, String.class)}.
*
* @param value
* the value to be encoded
* @param type
* the type of the value
* @return a JSON representation of the given value
*/
protected <U> JsonValue encode(U value, Class<U> type) {
return JsonCodec
.encode(value, null, type, getUI().getConnectorTracker())
.getEncodedValue();
}
/**
* Gets the {@link Grid} this renderer is attached to. Used internally for
* indicating the source grid of possible events emitted by this renderer,
* such as {@link RendererClickEvent}s.
*
* @return the grid this renderer is attached to or null if unattached
*/
@SuppressWarnings("unchecked")
protected Grid<T> getParentGrid() {
if (super.getParent() == null) {
return null;
}
return (Grid<T>) super.getParent().getParent();
}
}
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